The present invention relates to apparatus for supplying breathing gas to crew members of fighter aircraft and protecting them against the effects of acceleration.
For coping with the ever increasing ceiling and performance of fighter aircraft, complex protection apparatuses have been designed. However, they have limitations and fail to maintain full protection under all circumstances.
First of all, the apparatus should supply the crew member with breathing gas whose composition and pressure are adjusted automatically to the variations of altitude which, for aircraft under design, may be as high as 30,000 m, which implies either the use of a space suit, or a pressurized helmet and a suit provided with pockets in which gas pressure is maintained at high altitudes. In present day suits, the protection against acceleration effects is ensured by inflating pockets provided in the trousers of the suit when a high acceleration is detected, particularly when pulling out from a dive or during a tight turn such as are encountered in dog fight. The two functions are generally provided by entirely separate systems. The pockets of trousers intended for protection against acceleration are separate and distinct from those intended to ensure pressurization at altitude. The presence of two independent systems makes the device complex and uncomfortable for the pilot.
More important, the pockets for protection against accelerations remain entirely empty during normal flight. As a consequence, the response time of the device (i.e. the time delay between the reception of the inflation order and the moment when the pressure in the pockets of the g-suit is such that effective protection is achieved) is quite substantial.
Most of the present systems for protection against accel erations are supplied with air from a pressurized air supply device which is in addition to the oxygen storage system for breathing purpose. To simplify the installation, it has already been proposed supplying the acceleration protection system from the pressurized oxygen store on board the aircraft. But then the bulk and weight of stored oxygen is increased. An additional limitation is that a liquid oxygen converter can hardly supply the large instantaneous flow rates required for quasi instantaneous inflation of the pockets of the anti-g trousers.
It is an object of the invention to provide an improved apparatus in which the shortcomings of the prior systems are overcome, at least to a large extent. It is an other object to provide an apparatus having improved acceleration detection means, suitable for miniaturization. It is another important object to simplify the individual equipment of the crew members.
According to an aspect of the invention, there is provided a breathing and acceleration protection apparatus for the crew of fighter aircrafts, having a source of pressurized respiratory gas, anti-g regulator valve means having an input connected to said source and an output constructed to be connected to inflatable trouser pockets of a g-suit carried by a member of said crew, and a demand regulator arranged to deliver respiratory gas to said crew member, wherein said anti-g regulator valve means include an inertia body movable along a predetermined direction responsive to acceleration along said direction, valve means controlled by said inertia body and controlling the pressure in said pockets as an increasing function of the acceleration, and additional means responsive to the aircraft altitude for setting a pressure in said pockets at a value which increases with altitude in the absence of acceleration.
The set pressure in the pockets may be controlled by an altimetric capsule associated with an oxygen valve; it may also be controlled by a pressure bleed from the breathing regulator.
The inertia body may be a mass suspended by a diaphragm disposed perpendicularly to the direction of the accelerations to be detected and in a plane passing approximately through the center of gravity of the mass.
The regulator controlling the gas pressure in the pockets of the trousers may be provided with means for pre-inflating, under a limited pressure, the pockets of the trousers as soon as the flight controls of the aircraft are placed in a position which will cause an acceleration of the aircraft. The reaction time is thus considerably reduced and the crew members benefit from anti-g protection as soon as they are subjected to the acceleration, which is not the case at the present time. This arrangement is particularly easy to implement in the case of those aircrafts which comprise an electrical transmission control system, frequently called "fly by wire". The signal fed to the regulator may be derived from the control. A signal processing circuit, using for example an amplifier, a timer, possibly a correction network (proportional-derivative circuit) may be used for adapting the control to the particular type of aircraft concerned.
Whatever the solution, the protective suit may consist of anti-g trousers, whose pockets are also inflatable to ensure the necessary pressurization at high altitudes, and a pressurized waistcoat, without it being necessary to provide a pneumatic connection between trousers and waistcoat.
The invention will be better understood from a reading of the following description of particular embodiments.